Your requirements could not be resolved to an installable set of packages. Problem 1 - Root composer.json requires yiisoft/db-pgsql dev-master -> satisfiable by yiisoft/db-pgsql[dev-master]. - yiisoft/db-pgsql dev-master requires yiisoft/db dev-master -> found yiisoft/db[dev-master] but it does not match your minimum-stability.